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The antennas contained in mobile phones, including smartphones, emit radiofrequency (RF) radiation (non-ionizing "radio waves" such as microwaves); the parts of the head or body nearest to the antenna can absorb this energy and convert it to heat or to synchronised molecular vibrations (the term 'heat', properly applies only to disordered molecular motion).
Diagram of leaky feeder cable. A leaky feeder is a communications system used in underground mines and inside tunnels. [1] Manufacturers and cabling professionals use the term "radiating cable" [2] [3] [better source needed] [4] as this implies that the cable is designed to radiate: something that a typical coaxial cable is generally not intended to do.
Interference with the meaning of electromagnetic interference, also radio-frequency interference (EMI or RFI) is – according to Article 1.166 of the International Telecommunication Union ' s (ITU) Radio Regulations (RR) [8] – defined as "The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 7 February 2025. Claimed sensitivity to electromagnetic fields This article is about a pseudomedical diagnosis. For the recognized effects of electromagnetic radiation on human health, see Electromagnetic radiation and health. Electromagnetic hypersensitivity Idiopathic environmental intolerance ...
In a radio antenna, the feed line (feedline), or feeder, is the cable or other transmission line that connects the antenna with the radio transmitter or receiver.In a transmitting antenna, it feeds the radio frequency (RF) current from the transmitter to the antenna, where the energy in the current is radiated as radio waves.
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]
The primitive transmitters prior to 1897 had no resonant circuits (also called LC circuits, tank circuits, or tuned circuits), the spark gap was in the antenna, which functioned as the resonator to determine the frequency of the radio waves. [33] [43] [17]: p.352-353, 355–358 [44] These were called "unsyntonized" or "plain antenna" transmitters.
Path loss normally includes propagation losses caused by the natural expansion of the radio wave front in free space (which usually takes the shape of an ever-increasing sphere), absorption losses (sometimes called penetration losses), when the signal passes through media not transparent to electromagnetic waves, diffraction losses when part of the radiowave front is obstructed by an opaque ...